Hammer drill



June 1963 F. E. FLEISCHER ETAL 3,0 ,047

HAMMER DRILL 2 Sheets-Sheet 1 Filed Sept. 15, 1961 WVf/VTORS.

FZE/SCf/EQ E'DMPO TOPA/VEL/AMJR. BY

Way/tr.

AZTOP/VEV June 25, 1963 F. E. FLEiSCHER ETAL 3,095,047

HAMMER DRILL Filed Sept. 15. 1961 2 Sheets-Sheet 2 Q INVENTORS & F250 5. FLE/SCf/EQ fiwmw TOPAA/EL/AMJQ.

United States Patent 3,995,047 HAP/[MER DREL Fred E. Fleischer, Oalsmont, and Edward Topanelian, Jan,

Pittsburgh, Pa, assignors to Gulf Research 8: Development Company, Pittsburgh, Pan, a corporation of Dela- Ware Filed Sept. 15, 1961, set. No. 133,310 6 Claims. or. 173-137 This invention relates to well drills and in particular relates to a rotary type well drill having an improved fluid-actuated percussion mechanism.

In the well drilling art it is recognized that the addition of a percussive action at the drill bit increases the penetration rate of a rotary drill, particularly when drilling in hard formations, such as chert or limestone. It is also known that economic advantage is often achieved by drilling a smaller diameter hole. A number of rotary percussion drills have been proposed but none of the prior art rotary percussion drills are readily adaptable to small diameter sizes, and consequently a large part of the advantage of percussion drilling is lost. This shortcoming has been eliminated in the present invention which provides a simple, rugged rotary percussion drill that can be fabricated in small diameter sizes.

The advantages of the drill of this invention are attained by employing an annular valve inside a central opening in the main hammer. The structure of this invention provides unimpeded flow of drilling fluid through the central passageway of the hammer, and at the same time avoids any increase in diameter of the tool such as would be necessitated by the use of a valve external to the hammer. The construction provides for an excellent and highly reliable seal between the valve and its seat, provision being made to forcibly seat the valve in the event that an obstruction should lodge between the valve and its seat, and to provide a hydraulic clamping force to im prove the valve seal. Provision is also made for the hammer to forcibly unseat the valve at the proper phase of the operating cycle. The drill mechanism of this invention thereby provides a small diameter tool having a highly reliable hammer-actuating mechanism.

This invention is illustrated in the accompanying drawings which form a part of this specification, and in which FIGURE 1 is a longitudinal section taken through the upper portion of a preferred embodiment of the drill of this invention;

FIGURE 2 is a longitudinal section taken through the intermediate portion of the drill;

FIGURE 3 is a longitudinal section taken through the lower portion of the drill; and

FIGURES 4 to 9 are diagrammatical representations illustrating successive phases in the cyclic operation of the drill of this invention.

Reference is made to the drawings in which like numerals indicate the same element in the various views and diagrams.

Referring to FIGURES 1, 2, and 3, adapter 1 serves to connect the drill assembly of this invention to the conventional drill stem (not shown) by means of conventional drill-collar threads 2. The drill stem has a central passageway as is conventional for supplying drilling fluid to the drill bit and adapter 1 is also provided with a central passage 3 for the purpose of admitting the pressurized drilling fluid from the drill stem to the drill mechanism. A cylindrical housing 4 is fastened by threads 5 on the adapter 1, and a portion 6 of the adapter of reduced diameter extends into the housing 4 with an annular clearance 7 between them. The annular clearance 7 is sufficiently large to permit free flow of drilling fluid between the portion 6 of the adapter and the inside of 3fi=95fi47 Patented June 25, 1963 the housing 4. The area of annular clearance 7 is preferably substantially the same as that of passage 3. Diagonal openings 8 permit pressurized drilling fluid to pass from the passage 3 into the annular clearance 7. The lower end of the extension 6 of adapter 1 is bored out as indicated at 9 to form an inverted cup-like cylinder 10. The inner surface of the lip of cylinder it) is preferably provided with a replaceable wear sleeve 33 that is pressed or shrunk into cylinder 10.

The housing 4 is of a considerable length and contains the operating mechanism of the drill to be described in more detail later. The lower end of housing 4 (see FIGURE 3) is internally threaded at 11 and a bit stem retainer 12 is screwed to the lower end of housing 4. The bit stem retainer 12 has substantially the same external diameter as the housing 4. Retainer 12 serves to retain the bit stem 13, the latter having a certain degree of longitudinal sliding motion in the member 12. The bit stem 13 is provided at its lower end with threads 14 which are conventional for attaching any desired type of drill bit (not shown). The bit stem retainer 12 is provided with a hexagonal internal bore 15 in which a hexagonal shank on the bit stem 13 forms a sliding fit. The hexagonal arrangement '15 serves to transmit torque from the tool to the bit through the bit stem 13.

Above the hexagonal portion 15 the bit stem retainer 12 is provided with a cylindrical bore 16 in which a cylindrical extension of the bit stem may slide. A seal is provided between the bit stem and the retainer 12 by means of O-ring 17 retained in groove 18 in the cylindrical portion of the bit stem. Immediately above the cylindrical portion 16 of the bit stem is a portion 19 of reduced diameter and the bit stem is again enlarged at 2% terminating at an upper anvil surface 21. The diameter of enlargement 20 is no larger than the diameter of the cylindr-ical portion 16 of the bit stem. Prior to screwing the bit stem retainer 12 on the lower end of housing 4, the bit stem is inserted in the retainer 12 and there is placed around the portion 19 of reduced diameter the two halves of a split washer 22., and above this is placed a clamping spring 23 as shown. The housing 4 is provided with a shoulder 24 on its inner surface, and the clamping spring 23 abuts the shoulder 24 when the assembly is tightly screwed together. Thus upon assembly the split washer 22 is held against the top of the bit stem retainer 12 by the compression of clamping spring 23. The bit stem 13 is sealed against the member 12 but has a certain degree of vertical sliding movement due to the fact that the length of the region of reduced diameter 19 exceeds the axial length of split washer 22. At the same time the assembly is such as to provide transmission of torque from the housing 4 to the bit stem 13 via the hexagonal joint 15'. The upper surface 21 of the bit stem 13 serves as an anvil against which the valve seals as will become evident later, and upon which the hammer delivers its percussive blows. The diameter of the bit stern immediately below the surface '21 may be relieved slightly in order to allow for a certain amount of peening deformation during operation of the tool. The bit stem 13 is provided with a central opening 26 through which drilling fluid is discharged into the drill bit.

Located in the mechanism inside the housing 4 is an elongate annular hammer 3% that is provided with a central longitudinal passageway 31. The outside diameter of hammer 3%) is less than the inside diameter of the housing 4- in order to provide an annular space 58 between them and through which pressurized drilling fluid can flow. The upper end 32 (see FIGURE 1) of hammer 3t} fits into the lower end of cylinder 10 and forms a sliding seal against the sleeve 33 of cylinder Iii. A helical compression spring 34 may be placed inside the cylinder 10 to accelerate the hammer 30 downward after the latter has been lifted by the drilling fluid as will be explained. The spring 34 is not essential to operation of the drill of this invention, but is preferred in that it shortens the operating cycle thereby providing operation of the hammer 'at a higher frequency.

The lower end of hammer 39 (see FIGURE 3) is provided with internal threads 35 into which is screwed a hammer head 36. The hammer head 36 serves to hold in place the valve element 40. The valve 40 is annular in shape and has a central opening 41 through which fluid may pass from the central opening 31 in the hammer to the passageway 26 in the bit stem 13. The upper end of valve 40 is provided with a head 42 and below th s is a valve stem 43 of reduced diameter. The stem 43 of the valve 40 is a sliding fit in the internal bore of the hammer head 36. A helical compression spring 44 is placed between the head of the valve 42 and the top of the hammer head 36. Upward motion of the valve 40 is limited by the shoulder 45 where the central passage 31 of the hammer enlarges to the diameter 46 in which the valve head 42 and valve spring 44 are located. The lower end of valve 40 is provided with a cap 47 that is shrunk onto the valve stem 43 after assembly of the valve 49 and valve spring 44 in hammer head 36. The cap 47 thus serves to lock the valve assembly on the hammer head. The valve 40 has a limited degree of movement in the hammer head 36 as permitted by compression of spring 44 until the shoulder 48 strikes the top of the hammer head 36. The valve then is urged upward by the spring 44.

The hammer head 56 is provided over a portion of its outer surface with a plurality of guides 50 whose lands form a sliding fit with the inner surface of housing 4. The purpose of the guides 50 is to centralize the lower end of the hammer assembly in the housing 4. Free circulation of drilling fluid is provided from the annular space 58 (between the hammer 30 and the inside of housing 4, see FIGURE 2) into the region 51 below the hammer by the channels between the guides 50.

The central passage in the hammer head is bored out at 52 to accommodate the cap 47 of the valve assembly. The bore 52 is made somewhat longer in its axial dimension than the axial dimension of the cap 47 in order to provide a space 60 and to insure that the cap shall not strike the upper end of the bore 52, since such striking may tend to loosen the cap 47 from the valve stem 43.

Small openings 53 communicate between the annular the upper end of the bit stem and the lower end of the hammer head, and into the central channel 26 in the bit stem, whence it goes to the drill bit.

The axial dimension of the valve assembly is such that the entire valve assembly is slightly shorter than the distance from the lower end of the hammer head to the shoulder 45 in the hammer. As previously indicated, the cap 47 is slightly smaller in axial dimension than the enlargement 52 in which it slides. Accordingly, when the hammer assembly is hanging free, the spring 44 will urge the valve assembly to its uppermost position so that the valve head 42 is in contact with the shoulder 45 and the 7 bottom end of the valve cap is just slightly above the space 58 around the hammer and space 60 in the enlarged passageway 52 above the cap 47 of the valve assembly, and permit interchange of fluid so as to avoid trapping any drilling fluid in the bore 52 above the cap 47. Also the pressurized fluid that is admitted through openings 53 to the space 60 above the valve cap 47 exerts a downward force on the top of valve cap 47 and this force serves to seat the valve after the hammer lands.

At the lower end of the guides the body of the hammer head 36 is milled out in the area between the guides 50 to form recesses 55. The purpose of the recesses 55 will become evident upon explanation of the operating cycle.

The axial length of the hammer and hammer head are made such that when the hammer assembly is at its lowermost position and the bit stem 13 is also in its lowermost position, the hammer assembly will come to rest when the guides 50 rest on the top of spring 23 and the upper end 32 of the hammer will still be inside the sleeve 33. The axial dimensions of bit stem 13 are such that when it is in its lowermost position with the shoulder 56 resting on the top of split washer 22, the lower end of the hammer does not rest on the upper surface 21 of the bit stem but is supported on the spring 23. Due to the space provided by the recesses 55 there will then be free access of drilling fluid from the drill stern through passageway 3, openings 8, annular space 7, and annular space 58, through the recesses 55, past the clearance between bottom end of the hammer head.

FIGURES 4 to 9 illustrate successive phases in the cycle of operation of the drill shown in FIGURES 1 to 3. FIGURE 4 illustrates the relative configuration of the hammer and valve when the drill assembly is hanging at the end of the drill stem. In this situation the bit stem 13 falls to its lowermost position in which the enlargement 20 of the bit stem rests on top of the split washer 22 (see FIGURE 3). The hammer 39 also fails to its lowermost position and rests on the top of spring 24 (indicated in FIGURE 4 merely by the shoulder 24a). Drilling fluid from the drill stem passes through openings 3 into the annular space 7 and annular space 58, through the recesses 55, the space 57 between the bottom of the hammer and top of the bit stem (as previously explained), and out through the passageway 26 in the bit stem. When in this configuration insufficient force is developed to raise the hammer, and the mechanism is in an inoperative or bypass condition.

Upon reaching the bottom of the hole the assembly rests on the drill bit and bit stem 13 and this raises the bit stem 13 with respect to the housing 4 as shown in FIGURE 5. The hammer is also raised since it rests on top of the bit stem. Drilling fluid is now trapped in the annular space 58. Note that pressurized drilling fluid does not have access to the inside of cylinder 10. The pressurized drilling fluid therefore tends to lift the hammer 30 into the cylinder 10. Inasmuch as the outside diameter of the valve stem 43 is less than the internal diameter of sleeve 33, the pressure of the pressurized fluid around the hammer 30 effects an upward lifting force on the hammer causing it to move upward into cylinder 10. The valve however maintains its seal against the surface 21 on top of the bit stem by virtue of the downward hydraulic clamping action produced by the pressurized fluid on the upper surface of valve cap 47 as previously explained. Accordingly, the valve is not immediately lifted with the hammer, and this is shown in FIGURE 6.

As the hammer rises, the valve spring 44 is compressed and eventually the shoulder 48 strikes the top of the ham mer head 36, and this mechanically lifts the valve oif its seat. This is shown schematically in FIGURE 7.

As soon as the valve lifts off its seat as shown in FIG URE 7, the pressure difierential which acts to the hammer disappears since the drilling fluid may now escape from the annular space 58 into the. passageway 26 of the bit stem. The hammer begins to fall under the action of gravity (and the force of spring 34 which is not shown in FIGURES 4 to 9). The valve spring 44 in the meantime forces the valve upward in the hammer assembly to the upper limit of travel of the valve, aided by the inrush of fluid from below the valve which gives the valve an upward impetus. This configuration with the hammer falling is illustrated in FIGURE 8. The hammer then strikes the anvil surface 21 on top of the "bit stem as shown in FIGURE 9 and imparts its momentum to the bit stem and drill bit, thus providing a percussive blow to the latter.

Pressure of the drilling fluid through the passages 53 and bore 52 exerts a downward force on the valve cap 47 and aided by the downward momentum of the valve.

causes the latter to seal against its seat at the upper end of the bit stem as shown in FIGURE 9. This configuration is the same as that shown in FIGURE 5 and represents the completion of a cycle, which may then repeat, so that the hammer will strike a succession of percussive olows against the drill bit. Should it be desired to stop the hammering action and still maintain circulation of the fluid in the hole, it is merely necessary to raise the drill housing sufiicient-ly ltO achieve the configuration shown in FIGURE 4, whereupon percussive action will cease.

The construction of the drill of this invention has the advantage that the parts that suffer the most wear are quickly and easily replaced and are simple in construction. Wearing parts are the valve 43 and the hammer head 36 in which the valve slides and which also carries the guides 5! All of these parts may be replaced by simply removing the hammer and valve assembly from the housing and unscrewing only the threads 35 to remove the hammer head assembly, which is replaced with a new assembly including the complete new valve and new guides. Thus this single operation permits replacing all of these worn elements, and this simplicity is an important desideratum in field operation of the drill.

What we claim as our invention is:

1. A fluid-operated well-drilling mechanism comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in the top of said housing, an elongate annular hammer in said housing and slidably disposed in and sealed against the inside of said cylinder, said hammer having a longitudinal central passage therethrough, means afiording operating fluid access to the interior of said housing below said hammer, an annular valve having a longitudinal passage therethrough slidably disposed in and sealed against said passage in said hammer, the outside diameter of said valve being less than the inside diameter of said cylinder, resilient means in said hammer urging said valve upward in said passage in said hammer, a stop on said hammer restricting upward movement of said Valve with respect to said hammer, said stop being positioned so that when said valve is in its uppermost position with respect to said hammer the bottom end of said valve is proximately above the bottom end of said hammer, an upwardly facing shoulder on said valve, a lateral passageway through said hammer affording operating fluid access to said upwardly facing shoulder of said valve, and a bit stem slidably disposed in and sealed against said housing below said hammer and having a longitudinal central passage, the upper end of said bit stem being disposed to be struck by the lower end of said hammer.

2. A fluid-operated well-drilling mechanism comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in the top of said housing, an elongate annular hammer in said housing and slidably disposed in and sealed against the inside of said cylinder, said hammer having a longitudinal central passage therethrough, means affording operating fluid access to the interior of said housing below said hammer, an annular valve having a longitudinal passage therethrough slidably disposed in and sealed against said passage in said hammer, the outside diameter of said valve being less than the inside diameter of said cylinder, an upwardly facing shoulder on said valve, a lateral passageway through said hammer aflording operating fluid access to said upwardly facing shoulder of said valve, resilient means in said hammer urging said valve upward in said passage in said hammer, a bit stem slidably disposed in and sealed against said housing below said hammer and having a longitudinal central passage, the upper end of said bit stem being disposed to be struck by the lower end of said hammer, and a valve stop on said hammer restricting upward movement of said valve with respect to said hammer, said valve stop being positioned so that when said valve is in its uppermost position with respect to said hammer and the bottom end of said hammer is in contact with said bit stem the bottom end of said valve is proximately short of contacting said bit stem.

3. A fluid-operated well-drilling mechanism comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in the top of said housing, an elongate annular hammer in said housing and slidably disposed in and sealed against the inside of said cylinder, said hammer having a longitudinal central passage therethrough, means affording operating fluid access to the interior of said housing below said hammer, an annular valve having a longitudinal passage therethrough slidably disposed in and sealed against said passage in said hammer, the outside diameter of said valve being less than the inside diameter of said cylinder, resilient means in said hammer urging said valve upward in said passage in said hammer, a first stop on said hammer restricting upward movement of said valve with respect to said hammer, said first stop being positioned so that when said valve is in its uppermost position with respect to said hammer the bottom end of said valve is proximately above the bottom end of said hammer, an upwardly facing shoulder on said valve, a lateral passageway through said hammer affording operating fluid access to said upwardly facing shoulder of said valve, a bit stem slidably disposed in and sealed against said housing below said hammer and having a longitudinal central passage, the upper end or" said bit stem being disposed to be struck by the lower end of said hammer, and a second stop on said housing arresting downward motion of said hammer at a position above said bit stem when said bit stem is in its lowermost position, said second stop being adapted to permit passage of operating fluid.

4. A fluid-operated well-drilling mechanism comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in the top of said housing, annular clearance between said housing and said cylinder afiording operating fluid access to the interior of said housing below said cylinder, an elongate annular hammer in said housing and slidably disposed in and sealed against the inside of said cylinder, said hammer having a longitudinal central passage therethrough, annular clearance between said housing and said hammer, an vannular valve having a longitudinal passage therethrough slidably dis posed in and sealed against said passage in said hammer, the outside diameter of said valve being less than the inside diameter of said cylinder, resilient means in said hammer urging said valve upward in said passage in said hammer, a stop on said hammer restricting upward movement of said valve with respect to said hammer, said stop being positioned so that when said valve is in its uppermost position with respect to said hammer the bottom end of said valve is proximately above the bottom end of said hammer, an upwardly facing shoulder on said valve, a lateral passageway through said hammer affording operating fluid access to said upwardly facing shoulder of said valve, and a bit stem slidably disposed in and sealed against said housing below said hammer and having a longitudinal central passage, the upper end of said bit stem being disposed to be struck by the lower end of said hammer.

5. A fluid-operated well-drilling mechanism comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in the top of said housing, an elongate annular hammer smaller in diameter than the inside diameter of said housing and slidably disposed in and sealed against the inside of said cylinder, said hammer having a longitudinal central passage therethrough, means aifording operating fluid access to the interior of said housing below said hammer, a spring in said cylinder urging said hammer downward, an annular valve having a longitudinal passage therethrough slidably disposed in and sealed against said passage in said hammer, the outside diameter of said valve being less than the inside diameter of said cylinder, resilient means in said hammer urging said valve upward in said passage in said hammer, a stop on said hammer restricting upward movement of said valve with respect to said hammer, said stop being positioned so that when said valve is in its uppermost position with respect to said hammer the bottom end of said valve is proximately above the bottom end of said hammer, an upwardly facing shoulder on said valve, a lateral passageway through said hammer affording operating fluid access to said upwardly facing shoulder of said Valve, and a bit stem slidably disposed in and sealed against said housing below said hammer and having a longitudinal central passage, the upper end of said bit stem being disposed to be struck by the lower end of said hammer.

6. A fluid-operated Well-drilling mechanism comprising a tubular housing, an inverted cup-like cylinder longitudinally mounted in the top of said housing, an elongate annular hammer in said housing and slidably disposed in and sealed against the inside of said cylinder, said hammer having a longitudinal central passage therethrough, means aflording operating fluid access to the interior of said housing below said hammer, an annular valve having a longitudinal passage therethrough slidably disposed in and sealed against said passage in said hammer, the outside diameter of said valve being less than the inside diameter of said cylinder, resilient means in said hammer urging said valve upward in said passage in said hammer, a stop on said hammer restricting upward movement of said valve with respect to said hammer, said stop being positioned so that when said valve is in its upppermost position with respect to said hammer the bottom end of said valve is proximately above the bottom end of said hammer, an upwardly facing shoulder on said valve, means afiording operating fluid access to said upwardly facing shoulder of said valve when said valve is in contact with said bit stem, and a bit stem slidably disposed in and sealed against said housing below said hammer and having a longitudinal central passage, the upper end of said bit stem being disposed to be struck by the lower end of said hammer.

References Cited in the file of this patent UNITED STATES PATENTS 2,580,203 Topanelian Dec. 25, 1951 2,661,928 Topanelian Dec. 8, 1953 2,851,251 Mori Sept. 9, 1958 

6. A FLUID-OPERATED WELL-DRILLING MECHANISM COMPRISING A TUBULAR HOUSING, AN INVERTED CUP-LIKE CYLINDER LONGITUDINALLY MOUNTED IN THE TOP OF SAID HOUSING, AN ELONGATED ANNULAR HAMMER IN SAID HOUSING AND SLIDABLY DISPOSED IN AND SEALED AGAINST THE INSIDE OF SAID CYLINDER, SAID HAMMER HAVING A LONGITUDINAL CENTRAL PASSAGE THERETHROUGH, MEANS AFFORDING OPERATING FLUID ACCESS TO THE INTERIOR OF SAID HOUSING BELOW SAID HAMMER, AN ANNULAR VALVE HAVING A LONGITUDINAL PASSAGE THERETHROUGH SLIDABLY DISPOSED IN AND SEALED AGAINST SAID PASSAGE IN SAID HAMMER, THE OUTSIDE DIAMETER OF SAID VALVE BEING LESS THAN THE INSIDE DIAMETER OF SAID CYLINDER, RESILIENT MEANS IN SAID HAMMER URGING SAID VALVE UPWARD IN SAID PASSAGE IN SAID HAMMER, A STOP ON SAID HAMMER RESTRICTING UPWARD MOVEMENT OF SAID VALVE WITH RESPECT TO SAID HAMMER, SAID STOP BEING POSITIONED SO THAT WHEN SAID VALVE IS IN ITS UPPERMOST POSITION WITH RESPECT TO SAID HAMMER THE BOTTOM END OF SAID VALVE IS PROXIMATELY ABOVE THE BOTTOM END OF SAID HAMMER, AN UPWARDLY FACING SHOULDER ON SAID VALVE, MEANS AFFORDING OPERATING FLUID ACCESS TO SAID UPWARDLY FACING SHOULDER OF SAID VALVE WHEN SAID VALVE IS IN CONTACT WITH SAID BIT STEM, AND A BIT STEM SLIDABLY DISPOSED IN AND SEALED AGAINST SAID HOUSING BELOW SAID HAMMER AND HAVING A LONGITUDINAL CENTRAL PASSAGE, THE UPPER END OF SAID BIT STEM BEING DISPOSED TO BE STRUCK BY THE LOWER END OF SAID HAMMER. 